Two-dimensional bidirectional object layout

Autor:	Yoav Zibin, William Pugh, Grant E. Weddell, Joseph Gil
Rok vydání:	2008
Předmět:	Object-oriented programming Computer science Multiple inheritance Parallel computing computer.software_genre Object (computer science) Identifier Inheritance (object-oriented programming) Virtual inheritance Benchmark (computing) Compiler Algorithm computer Software
Zdroj:	ACM Transactions on Programming Languages and Systems. 30:1-38
ISSN:	1558-4593 0164-0925
DOI:	10.1145/1387673.1387677
Popis:	Object layout schemes used in C++ and other languages rely on (sometimes numerous) compiler generated fields. We describe a language-independent object layout scheme, which is space optimal, that is, objects are contiguous, and contain no compiler generated fields other than a single type identifier. As in C++ and other multiple inheritance languages such as CECIL and DYLAN, the new scheme sometimes requires extra levels of indirection to access some of the fields. Using a data set of 28 hierarchies, totaling almost 50,000 types, we show that this scheme improves field access efficiency over standard implementations, and competes favorably with (the non-space-optimal) highly optimized C++ specific implementations. The benchmark includes an analytical model for computing the frequency of indirections in a sequence of field access operations. Our layout scheme relies on whole-program analysis, which requires about 10 microseconds per type on a contemporary architecture (Pentium III, 900Mhz, 256MB machine), even in very large hierarchies. We also present a layout scheme for separate compilation using the user-annotation of virtual inheritance edge that is used in C++.
Databáze:	OpenAIRE
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